Understanding Your Pool Chemistry

Pool chemistry sounds intimidating, but it boils down to a few key numbers. Get these right, and your pool stays clear. Let them drift, and you’ll be fighting algae, cloudy water, or worse.

The Big Three

Free Chlorine (FC): 2–4 ppm

Chlorine is your sanitizer. It kills bacteria, algae, and anything else you don’t want growing in your water. “Free” chlorine is the active, working chlorine — not the stuff that’s already been used up.

• Too low: Algae and bacteria thrive. Green water incoming.
• Too high: Skin and eye irritation, bleached swimsuits.

pH: 7.4–7.6

pH measures how acidic or basic your water is. It directly affects how well your chlorine works.

• Too low (acidic): Corrodes equipment, etches plaster, irritates skin.
• Too high (basic): Chlorine becomes ineffective, water gets cloudy, scale forms.

Total Alkalinity (TA): 80–120 ppm

Alkalinity acts as a buffer for pH. If alkalinity is in range, pH stays more stable.

• Too low: pH bounces around wildly.
• Too high: pH drifts up, water clouds, scale forms.

Central Texas Specifics

Our tap water runs hard — high calcium and high alkalinity. You’ll typically need to:

• Add muriatic acid regularly to control pH and TA
• Watch calcium hardness (aim for 200–400 ppm)
• Be aware that evaporation concentrates minerals — top off with fresh water regularly

Testing

Get a good liquid test kit (Taylor K-2006 is the gold standard) or reliable test strips. Test at least weekly, more often after heavy rain, parties, or extreme heat.

Need help dialing in your chemistry? The Pool Police tests and balances your water every single visit. Call (512) 300-4136.